Semileptonic decays B->(pi,rho)e nu in relativistic quark model

Quark model results for the B --> pi, rho decays are analysed, making use of the dispersion formulation of the model: The form factors at q(2) > 0 are expressed as relativistic invariant double spectral representation over invariant masses of the initial and final mesons through their light-cone wave functions. The dependence of the results on the quark model parameters is studied. For various versions of the quark model the ranges Gamma(<(B)over bar (0)> --> pi(+)e<(nu) over bar> = (7 +/- 2) x 10(12)\V-ub\(2) s(-1) Gamma(<(B)over bar (0)> --> rho(+)e<(nu) over bar>/Gamma(<(B)over bar (0)> --> pi(+)e<(nu) over bar> = 1.45 +/- 0.1, and Gamma(L)/Gamma(T) = 0.7 +/- 0.08 are found. The effects of the constituent quark transition form factor are briefly discussed.